HBO's True Detective is just the latest in a long line of art steeped in the southern gothic style. America might look like a place of relative civility, but scrape away the surface and there be monsters. Certainly, this is meat and drink for Seattle dark folk musician King Dude. "I love it," says Dude, real name Thomas Jefferson Cowgill. "A gritty detective series about ritual murders set in the 1980s during the rise of Satanic hysteria… it's like the writers crawled into my brain and made a show."

As King Dude, Cowgill plays folk, country and blues mired in doom and dread; a sound so dark we might have to downgrade Johnny Cash from The Man In Black to The Man In Medium Grey. Live, Cowgill and band take to the stage in front of a stars and stripes flag daubed in black, playing songs like Lay Down In Bedlam, Cloven Hooves (Of Fear) and You Can Break My Heart. "But please don't break the rest of me…" pleads Cowgill on the latter, like Roy Orbison being held at gunpoint.

Since 2003, Cowgill has fronted Seattle death metallers Book Of Black Earth. But folk is in his blood – his father was a fingerpicking guitarist in the vein of John Fahey – and when he decided to embark on a solo project, he says, it was with the rationale that "one-man metal bands are kind of difficult to pull off compared to one-man folk bands". King Dude is not, by and large, a vessel for venting feelings. "Those incredibly personal songs people write about breaking up just make my skin crawl," he says. Instead, Cowgill's songs toy darkly with the narrative folk tradition. On the brilliantly sinister Barbara Anne from last year's Burning Daylight LP, he's a patsy under the spell of a femme fatale, singing of slaughter and arson in a sinister gurgle that sounds like he's just about ready to be measured up for a casket.

Cowgill's stated aim on new album Fear was to make "the most horrifying music I could". Cacophonous lead single Fear Is All You Know, with its nightmarish, NSFW video set in an S&M strip joint, certainly fits the bill. But Fear also finds Cowgill writing about himself for the first time. "Sometimes, I'm the protagonist or narrator, but in a situation that hasn't happened to me personally. It's as close as I'll get to writing songs about my personal life."

Outside of King Dude, Cowgill runs clothing label Actual Pain, which sells hoodies, snapbacks and leggings emblazoned with pentagrams and inverted crucifixes. "I love religion and spirituality, good or bad," he says. To grasp the true meaning of Fear, he says, listeners need to enact a ritual of their own, using the perception-warping packaging of the gatefold vinyl. "You can listen to the record on its own and enjoy it just fine. But to really experience it, you have to hold the sleeve up in a mirror while listening to the record beginning to end."

Nobody will blame you, though, if you chicken out and decide to stick with the CD.